1. Field of the Invention
The invention generally involves the field of technology pertaining to apparatus for cutting agricultural products into reduced size portions. More specifically, the invention relates to an improved knife assembly for use in a water gun whereby potato strips may be cut from whole potatoes for the production of french fries.
2. Description of the Prior Art
Hydraulic cutting systems are well known in the art for cutting or slicing agricultural products, particularly potatoes into slabs or strips. A system of this type is often referred to as a water gun and operates by pumping a mixture of water and the product to be cut through a pipe. The product is propelled at a fairly high rate of speed and caused to impact against a stationary knife assembly which cuts the product into the required size portions during its travel through the pipe. The resulting mixture of water and cut product is then discharged for separating the product from the water. In the production of french fries, such a system is generally capable of propelling the water and potato mixture through the knife assembly at approximately 55 feet per second and realize a production capacity of approximately 1000 pounds per minute.
The stationary knife assembly utilized in a typical water gun is defined by a cutting head block onto which a plurality of elongate knife elements are secured in parallel pairs that are disposed in a staggered relationship and at a 90.degree. offset with respect to adjacent pairs of knife elements. The cutting edge of the knife elements therefore collectively define a plurality of rectangular-shaped boxes for producing strips of the product having corresponding transverse cross-sectional configurations. The interengagement of adjacent knife elements is accomplished by providing each knife element with at least one open slot in its base portion and at least one open slot in its blade portion so that the blade portion of one knife element may be interengaged within the corresponding base portion slot of an adjacent knife element. The knife elements disposed at the furthermost upstream end of the head block are only provided with slots in their base portions, while the knife elements disposed at the furthermost downstream end of the head block are only provided with slots in their blade portions.
During the cutting operation, the high speed at which the product is impacted against the knife assembly and the often asymmetrical configuration of the product being cut tend to impart considerable stress to the individual knife elements of the assembly, particularly when the product does not impact directly at the center of the assembly. This stress results in a twisting of the knife elements from side to side, which in turn results in the bending of the sharp cutting edge corner portions of the slots in the blade portions of the knife elements. When this occurs, the resulting bent corner portions tear the sides of the potato strips as they are being cut, thereby producing an inferior product. Moreover, the bent corner portions also impair the proper sharpening of the knife elements after they become dull, and require that the affected knife elements be either repaired or discarded.
Some examples of water guns utilizing stationary knife assemblies of the type described herein are disclosed by the Lamb et al U.S. Pat. No. 3,116,772; Hodges et al U.S. Pat. No. 4,135,002; and Winslow U.S. Pat. No. 4,423,652.